Technical Abstract:
Beta-conglycinin (7S) and glycinin (11S) protein fractions have different functional properties related to gel formation, thermal stability and emulsification. Heat and calcium induced coagulum (tofu gel), made from the 11S fraction is harder than that from the 7S fraction. Beta-conglycinin is thermally more unstable than glycinin, but its emulsifying and emulsion-stabilizing abilities are better than those of glycinin. Genetic studies revealed variation on protein fractions and subfractions, and cultivars with high levels of 7S or 11S fractions are available. To determine protein fraction content, 90 Brazilian soybean cultivars were sowed in 2001 in Ponta Grossa, Paraná state (latitude 25º05' S), were analyzed. Effects of the sowing location were determined in cv. MG/BR 46 (Conquista), sowed in 16 locations of Minas Gerais and Goiás states, and in cv. IAS 5 sowed in 12 locations of Paraná and São Paulo states. Protein fractions were analyzed by eletrophoresis SDS-PAGE and the protein bands were quantitated in a Molecular Dynamics scanning densitometer. The 11S/7S ratio for the 90 cultivars was significantly different in a range of 2.76% to 1.17%, respectively for cvs. MS/BRS 169 (Bacuri) and BR-8 (Pelotas). Beta-conglycinin (7S) protein subfractions alpha', alpha, and beta were, respectively, 4.1, 6.6, and 3.3% for cv. MS/BRS 169 (Bacuri), and 5.5, 10.1, 7.7% for cv. BR-8 (Pelotas). Glycinin (11S) acidic and basic subfractions were respectively 22.1 and 16.8% for cv. MSBRS 169, and 14.5 and 12.9% for cv. BR-8. Therefore, cv. MS/BRS 169 seems to be a good material for gel formation. This cultivar may be used as a genetic source to increase glycinin content in soybean breeding programs. Among the 16 locations, cv. MG/BRS 46 showed 2.2 to 1.3% for 11S/7S ratio, while cv. IAS 5 showed a range of 2.4 to 1.6%. Breeding and cultivation management are important tools to obtain soybean cultivars with different beta-conglycinin (7S) and glycinin (11S) protein fraction content, which will make them suitable for different uses.